Date post: | 13-Jan-2016 |
Category: |
Documents |
Upload: | amanda-french |
View: | 213 times |
Download: | 0 times |
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 1
Chapter 9Chapter 9
The Endocrine System
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 2
Mechanisms of Hormone ActionMechanisms of Hormone Action
• Endocrine glands secrete chemicals (hormones) into the blood
• Hormones perform general functions of communication and control but a slower, longer-lasting type of control than that provided by nerve impulses
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 3
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 4
Mechanisms of Hormone Action Mechanisms of Hormone Action
• Cells acted on by hormones are called target organ cells
• Protein or Nonsteroid hormones (first messenger) bind to receptors on the target cell membrane, triggering second messengers to affect the cell’s activities
• Steroid hormones bind to receptors within the target cell nucleus and influence cell activity by acting on DNA
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 5
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 6
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 7
Regulation of Hormone SecretionRegulation of Hormone Secretion
• Hormone secretion is controlled by homeostatic feedback
• Negative feedback—mechanisms that reverse the direction of a change in a physiologic system
• Positive feedback—(uncommon) mechanisms that amplify physiologic changes
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 8
• Prostaglandins (PGs) are powerful substances found in a wide variety of body tissues
• PGs are often produced in a tissue and diffuse only a short distance to act on cells in that tissue
ProstaglandinsProstaglandins
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 9
ProstaglandinsProstaglandins
• Several classes of PGs include prostaglandin A (PGA), prostaglandin E (PGE), and prostaglandin F (PGF)
• PGs influence many body functions, including respiration, blood pressure, gastrointestinal secretions, and reproduction
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 10
Pituitary GlandPituitary Gland
• Anterior pituitary gland (adenohypophysis)
• Topic hormones- stimulate other glands Names of major hormones
Thyroid-stimulating hormone (TSH) Adrenocorticotropic hormone (ACTH) Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Growth hormone (GH) Prolactin hormone (PH)
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 11
Pituitary GlandPituitary Gland
Functions of major hormones TSH—stimulates growth of the thyroid gland; also
stimulates it to secrete thyroid hormone ACTH—stimulates growth of the adrenal cortex and
stimulates it to secrete glucocorticoids FSH—initiates growth of ovarian follicles each month in
the ovary and stimulates one or more follicles to develop to the stage of maturity and ovulation; FSH also stimulates estrogen secretion by developing follicles; stimulates sperm production in the male
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 12
Pituitary GlandPituitary Gland
LH—acts with FSH to stimulate estrogen secretion and follicle growth to maturity; causes ovulation; causes luteinization of the ruptured follicle and stimulates progesterone secretion by corpus luteum; causes interstitial cells in the testes to secrete testosterone in the male
GH—stimulates growth by accelerating protein anabolism; also accelerates fat catabolism and slows glucose catabolism; by slowing glucose catabolism, tends to increase blood glucose to higher than normal level (hyperglycemia)
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 13
Pituitary GlandPituitary Gland
Prolactin or lactogenic hormone—stimulates breast development during pregnancy and secretion of milk after the delivery of the baby
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 14
Pituitary GlandPituitary Gland
• Posterior pituitary gland (neurohypophysis) Names of hormones
Antidiuretic hormone (ADH) Oxytocin
Functions of hormones ADH—accelerates water absorption from urine in the kidney tubules into the blood, thereby decreasing urine secretion
Oxytocin—stimulates the pregnant uterus to contract; may initiate labor; causes glandular cells of the breast to release milk into ducts
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 15
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 16
HypothalamusHypothalamus
• Actual production of ADH and oxytocin occurs in the hypothalamus
• After production in the hypothalamus, hormones pass along axons into the pituitary gland
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 17
HypothalamusHypothalamus
• The secretion and release of posterior pituitary hormones are controlled by nervous stimulation
• The hypothalamus controls many body functions related to homeostasis (temperature, appetite, and thirst)
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 18
Thyroid GlandThyroid Gland
• Names of hormones Thyroid hormone—thyroxine (T4) and triiodothyronine (T3)
Calcitonin—decreases the blood calcium concentration by inhibiting breakdown of bone, which would release calcium into the blood
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 19
Parathyroid GlandParathyroid Gland
• Name of hormone—parathyroid hormone (PTH)
• Function of hormone—increases blood calcium concentration by increasing the breakdown of bone with the release of calcium into the blood
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 20
Antagonistic Hormones & Negative Feedback:Thyroid Calcitoninvs. Parathyroid PTH
Antagonistic Hormones & Negative Feedback:Thyroid Calcitoninvs. Parathyroid PTH
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 21
Adrenal GlandsAdrenal Glands
• Adrenal cortex Names of hormones (corticoids)
Glucocorticoids (GCs)—chiefly cortisol (hydrocortisone)
Mineralocorticoids (MCs)—chiefly aldosterone
Sex hormones—small amounts of male hormones (androgens) secreted by adrenal cortex of both sexes
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 22
Adrenal GlandsAdrenal Glands
• Three cell layers (zones) Outer layer, secretes mineralocorticoids Middle layer, secretes glucocorticoids Inner layer, secretes sex hormones
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 23
Adrenal GlandsAdrenal Glands
• Mineralocorticoids—increase blood sodium and decrease body potassium concentrations by accelerating kidney tubule reabsorption of sodium and excretion of potassium
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 24
Adrenal GlandsAdrenal Glands
• Functions of glucocorticoids Help maintain normal blood glucose concentration by increasing gluconeogenesis—the formation of “new” glucose from amino acids produced by the breakdown of proteins, mainly those in muscle tissue cells; also the conversion to glucose of fatty acids produced by the breakdown of fats stored in adipose tissue cells
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 25
Adrenal GlandsAdrenal Glands
Play an essential part in maintaining normal blood pressure—make it possible for epinephrine and norepinephrine to maintain a normal degree of vasoconstriction, a condition necessary for maintaining normal blood pressure
Act with epinephrine and norepinephrine to produce an antiinflammatory effect, to bring about normal recovery from inflammation of various kinds
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 26
Adrenal GlandsAdrenal Glands
• Produce antiimmunity, antiallergy effect; bring about a decrease in the number of lymphocytes and plasma cells and therefore a decrease in the amount of antibodies formed
• Secretion of glucocorticoid quickly increases when the body is thrown into a condition of stress; high blood concentration of glucocorticoids, in turn, brings about many other stress responses
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 27
Adrenal GlandsAdrenal Glands
• Adrenal medulla Names of hormones—epinephrine (adrenaline) and norepinephrine
Functions of hormones—help the body resist stress by intensifying and prolonging the effects of sympathetic stimulation; increased epinephrine secretion is the first endocrine response to stress
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 28
Pancreatic IsletsPancreatic Islets
• Names of hormones Glucagon—secreted by alpha cells
Insulin—secreted by beta cells
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 29
Pancreatic IsletsPancreatic Islets
• Functions of hormones Glucagon increases the blood glucose level by accelerating liver glycogenolysis (conversion of glycogen to glucose)
Insulin decreases the blood glucose by accelerating the movement of glucose out of the blood into cells, which increases glucose metabolism by cells
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 30
Female Sex GlandsFemale Sex Glands
The ovaries contain two structures that secrete hormones—the ovarian follicles and the corpus luteum• Effects of estrogen (feminizing hormone) Development and maturation of breasts and external genitals
Development of adult female body contours
Initiation of menstrual cycle
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 31
Male Sex GlandsMale Sex Glands
The interstitial cells of the testes secrete the male hormone testosterone• Effects of testosterone (masculinizing hormone) Maturation of external genitals Beard growth Voice changes at puberty Development of musculature and body contours typical of the male
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 32
ThymusThymus
• Name of hormone—thymosin• Function of hormone—plays an important role in the development and function of the body’s immune system
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 33
PlacentaPlacenta
• Name of hormones—chorionic gonadotropins, estrogens, and progesterone
• Functions of hormones—maintain the corpus luteum during pregnancy
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 34
Pineal GlandPineal Gland
• A small gland near the roof of the third ventricle of the brain Glandular tissue predominates in children and young adults
Becomes fibrous and calcified with age
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 35
Pineal GlandPineal Gland
• Called third eye because its influence on secretory activity is related to the amount of light entering the eyes
• Secretes melatonin, which: Inhibits ovarian activity Regulates the body’s internal clock
Copyright © 2004. Mosby Inc. All Rights Reserved. Slide 36
Other Endocrine StructuresOther Endocrine Structures
• Many organs (for example, the stomach, intestines, and kidneys) produce endocrine hormones
• The atrial wall of the heart secretes atrial natriuretic hormone (ANH), which stimulates sodium loss from the kidneys
• Fat-storing cells secrete leptin, which controls how full or hungry we feel